The invention relates to an auto-igniting, four-cycle, piston-type internal combustion engine. Engines of this kind are also known as Diesel engines.
In a known internal combustion engine of this type (German Democratic Republic Pat. No. 91,936), a cylindrical depression is disposed in the center of the piston, coaxial with its longitudinal axis, and openings directed diagonally downward from the piston top land into this depression, the openings being inclined in such a manner that the gas jets flowing through them into the depression, toward the end of the compression stroke, are intended to generate in the depression a vortex flow running approximately parallel to the piston top. The high flow losses of the gas flows which pass through the openings are disadvantageous. Furthermore, toward the end of the compression stroke, gas also flows in substantial quantities axially and radially into the depression approximately radially from all sides and this action hinders the formation of an effective vortex flow in the depression. Combustion is also insufficient in such an engine, with the result that a substantial quantity, in percentage terms, of harmful, partially combusted components is emitted.